Vibrational catheter devices and methods for making same

ABSTRACT

A vibrational catheter for disrupting obstructions in lumens such as blood vessels includes an elongate flexible catheter body having a proximal end, a distal end and at least one lumen extending longitudinally therethrough, a vibrational transmission member extending longitudinally through the lumen of the catheter body and having a proximal end and a distal end, and a transition connector attached to the proximal end of the vibrational transmission member for coupling the transmission member with a vibrational energy source. The transition connector includes a bore into which the proximal end of the vibrational transmission member extends. The proximal end of the vibrational transmission member is attached within the bore of the transition connector with variable attachment forces such that the transition connector exerts a lowest amount of attachment force on an attached distal-most portion of the vibrational transmission member housed within the bore.

This application is related to the following U.S. patent application Ser. No. 10/229,371, filed Aug. 26, 2002, entitled “Ultrasound Catheter for Disrupting Blood Vessel Obstructions”; Ser. No. 10/345,078, filed Jan. 14, 2003, entitled “Ultrasound Catheter and Methods for Making and Using Same”; Ser. No. 10/375,903, filed Feb. 26, 2003, entitled “Ultrasound Catheter Apparatus”; Ser. No. 10/410,617, filed Apr. 8, 2003, entitled “Improved Ultrasound Catheter Devices and Methods”; Ser. No. 10/722,209, filed Nov. 24, 2003, entitled “Steerable Ultrasound Catheter” and Ser. No. 10/927,966, filed Aug. 26, 2004, entitled “Improved Ultrasound Catheter Devices and Methods”. The full disclosures of all of the above-listed patent applications are all hereby incorporated by reference.

BACKGROUND OF THE INVENTION

The present invention relates generally to medical devices and methods. More specifically, the present invention relates to vibrational catheter devices and methods for treating occlusive intravascular lesions.

Catheters employing various types of vibration transmitting members have been successfully used to ablate or otherwise disrupt obstructions in blood vessels. Specifically, ablation of atherosclerotic plaque or thromboembolic obstructions from peripheral blood vessels such as the femoral arteries has been particularly successful. Various vibrational catheter devices have been developed for use in ablating or otherwise removing obstructive material from blood vessels. For example, U.S. Pat. Nos. 5,267,954 and 5,380,274, issued to an inventor of the present invention and hereby incorporated by reference, describe ultrasound catheter devices for removing occlusions. Other examples of ultrasonic ablation devices for removing obstructions from blood vessels include those described in U.S. Pat. Nos. 3,433,226 (Boyd), 3,823,717 (Pohlman, et al.), 4,808,153 (Parisi), 4,936,281 (Stasz), 3,565,062 (Kuris), 4,924,863 (Sterzer), 4,870,953 (Don Michael, et al), and 4,920,954 (Alliger, et al.), as well as other patent publications W087-05739 (Cooper), W089-06515 (Bernstein, et al.), W090-0130 (Sonic Needle Corp.), EP316789 (Don Michael, et al.), DE3,821,836 (Schubert) and DE2438648 (Pohlman). While many vibrational catheters have been developed, however, improvements are still being pursued.

Typically, a vibrational catheter system for ablating occlusive material includes three basic components: an vibration energy generator, a transducer, and a vibrational catheter. The generator converts line power into a high frequency current that is delivered to the transducer. The transducer contains piezoelectric crystals which, when excited by the high frequency current, expand and contract at high frequency. These small, high-frequency expansions (relative to an axis of the transducer and the catheter) are amplified by the transducer horn into vibrational energy. The vibrations are then transmitted from the transducer through the vibrational catheter via a vibrational transmission member (or wire). The transmission member transmits the vibrational energy to the distal end of the catheter where the energy is used to ablate or otherwise disrupt a vascular obstruction.

To effectively reach various sites for treatment of intravascular occlusions, vibrational catheters of the type described above typically have lengths of about 150 cm or longer. To permit the advancement of such vibrational catheters through small and/or tortuous blood vessels such as the aortic arch, coronary vessels, and peripheral vasculature of the lower extremities, the catheters (and their respective ultrasound transmission wires) must typically be sufficiently small and flexible. Also, due to attenuation of ultrasound energy along the long, thin, ultrasound transmission wire, a sufficient amount of vibrational energy must be applied at the proximal end of the wire to provide a desired amount of energy at the distal end.

One continuing challenge in developing vibrational catheters for treating vascular occlusions is to provide adequate vibrational energy at the distal end of a catheter device while simultaneously minimizing stress on the vibrational transmission wire in the area where it connects with the transducer. Typically, the vibrational transmission wire is coupled with the transducer via some kind of connector. A portion of the transmission wire immediately adjacent the connector is often put under great stress and strain when sufficient vibrational energy is applied to provide the desired vibration at the distal end of the catheter. This stress and strain can cause overheating and unwanted wear and tear of the transmission member, thus leading to wire breakage and a shortened useful life of the catheter device.

Some vibrational catheter devices include one or more absorption members where the proximal end of the vibrational transmission wire attaches to a transducer connector. For example, one such absorption member is described in U.S. Pat. No. 5,382,228. Such absorption members, however, may have drawbacks, in that they may be prone to coming loose and disconnecting from the transducer connector, and would thus become a loosely moving body within the catheter, disrupting vibrational energy transmission and reducing the catheter's efficacy.

Therefore, a need exists for improved vibrational catheter devices and methods that provide ablation and/or disruption of obstructions in lumens, such as vascular lumens. Ideally, such vibrational catheters would provide a desired level of power at a distal end of the device while also preventing or reducing stress and strain placed on the proximal end of the vibrational transmission member. Also ideally, such devices would be easily manufactured and have as few moving parts as possible in the area of connection of the transmission member with the transducer connector. At least some of these objectives will be met by the present invention.

BRIEF SUMMARY OF THE INVENTION

In one aspect of the present invention, a vibrational catheter for disrupting obstructions in lumens such as blood vessels includes an elongate flexible catheter body having a proximal end, a distal end and at least one lumen extending longitudinally therethrough, a vibrational transmission member extending longitudinally through the lumen of the catheter body and having a proximal end and a distal end, and a transition connector attached to the proximal end of the vibrational transmission member for coupling the transmission member with a vibrational energy source. The transition connector includes a bore into which the proximal end of the vibrational transmission member extends. The proximal end of the vibrational transmission member is attached within the bore of the transition connector with variable attachment forces such that the transition connector exerts a lowest amount of attachment force on an attached distal-most portion of the vibrational transmission member housed within the bore.

In some embodiments, the vibrational energy source comprises a transducer, such as but not limited to an ultrasound transducer. In some embodiments, the transition connector may comprise multiple pieces attached together, while in other embodiments the transition connector comprises a one-piece extrusion. In one embodiment, the proximal connection member of the transition connector comprises threads, which are complementary to threads on the vibrational energy source. Alternatively, any other suitable connection device may be used.

In some embodiments, the transition connector comprises a distal portion tapered proximally to distally, the distal portion extending from a proximal terminus of the bore to the opening of the bore. In such embodiments, the vibrational transmission member may be attached within the bore by crimping the tapered distal portion of the transition connector so as to apply greater crimping force to a wider, proximal portion of the distal portion than to a narrower, distal portion of the distal portion. In alternative embodiments, the transition connector comprises a distal portion including a first stepped portion having a first radius and extending distally from a proximal terminus of the bore and a second stepped portion having a second radius smaller than the first radius and extending from a distal end of the first stepped portion to the distal opening of the bore. In these latter embodiments, the vibrational transmission member may be attached within the bore by crimping the first stepped portion, thus applying greater crimping force to the first stepped portion than the second stepped portion.

In another alternative embodiment, the bore comprises a first stepped portion having a first radius and extending distally from a proximal terminus of the bore and a second stepped portion having a second radius greater than the first radius and extending from a distal end of the first stepped portion to the distal opening of the bore. Optionally, in such an embodiment, the vibrational transmission member may be attached within the bore by crimping the transition connector, thus applying greater crimping force to the first stepped portion than the second stepped portion. In some cases, a space exists between the transmission member and the second stepped portion of the bore before crimping, and the space closes during crimping.

In another aspect of the present invention, a vibrational catheter for disrupting obstructions in lumens such as blood vessels includes an elongate flexible catheter body having a proximal end, a distal end and at least one lumen extending longitudinally therethrough, a vibrational transmission member extending longitudinally through the lumen of the catheter body and having a proximal end and a distal end, and a transition connector. The transition connector includes a proximal connection member for attaching the transition connector to a vibrational energy source and a bore having an opening in a distal end of, and extending into, the transition connector, for accepting the proximal end of the vibrational transmission member. The proximal end of the vibrational transmission member extends into and is attached within the distal bore of the transition connector such that the transition connector exerts a greater amount of attachment force on an attached proximal-most portion of the transmission member than on an adjacent portion of the transmission member immediately distal to the proximal-most portion. Various embodiments of this catheter may include any of the features described above.

In another aspect of the present invention, a method for making a vibrational catheter for disrupting obstructions in lumens such as blood vessels includes inserting a proximal end of a vibrational transmission member into a bore in a transition connector and crimping at least part of the transition connector to attach the proximal end of the vibrational transmission member within the bore. In this method, a variable amount of crimping force is applied to attach the vibrational transmission member within the bore, so that the transition connector exerts a lowest amount of attachment force on an attached distal-most portion of the vibrational transmission member housed within the bore.

In some embodiments, crimping is performed with a crimping tool having a contact surface parallel with the vibrational transmission member, and the greater amount of crimping force is applied via a shaped portion of the transition connector overlying the bore. In alternative embodiments, crimping is performed with a crimping tool having a contact surface parallel with the vibrational transmission member, and the greater amount of crimping force is applied via a shaped bore. In another alternative embodiment, crimping is performed with a tapered crimping tool having a contact surface that contacts a proximal portion of the transition connector overlying the bore before contacting a more distal portion of the transition connector overlying the bore. Alternatively, crimping may performed with two crimping members, a more proximal crimping member applying greater force than a more distal crimping member. In another alternative embodiment, crimping involves crimping a first portion of the transition connector overlying the proximal-most portion of the transmission member with a crimping tool, moving the crimping tool distally along the transition connector, and crimping a second portion of the transition connector overlying the adjacent portion of the transmission member.

These and other aspects and embodiments of the present invention are described in further detail below, in reference to the attached drawing figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a vibrational catheter system, according to an embodiment of the present invention;

FIG. 2 is a side view of a vibrational catheter device, according to an embodiment of the present invention;

FIG. 3 is cross-sectional side view of a proximal portion of a vibrational catheter device having heat dissipation means, according to an embodiment of the present invention;

FIGS. 4A and 4B are cross-sectional side views of a proximal portion of a vibrational transmission member coupled with a transition connector for connecting to a vibrational energy source, according to an embodiment of the present invention;

FIG. 4C is a perspective view of the vibrational transmission member and transition connector of FIGS. 4A and 4B;

FIGS. 5A and 5B are cross-sectional side views of a proximal portion of a vibrational transmission member coupled with a transition connector for connecting to a vibrational energy source, according to an alternative embodiment of the present invention;

FIG. 5C is a perspective view of the vibrational transmission member and transition connector of FIGS. 5A and 5B;

FIGS. 6A and 6B are cross-sectional side views of a proximal portion of a vibrational transmission member coupled with a transition connector for connecting to a vibrational energy source, according to an alternative embodiment of the present invention;

FIG. 6C is a perspective view of the vibrational transmission member and transition connector of FIGS. 6A and 6B;

FIGS. 7A and 7B are cross-sectional side views of a proximal portion of a vibrational transmission member coupled with a transition connector for connecting to a vibrational energy source, according to an alternative embodiment of the present invention;

FIGS. 8A and 8B are cross-sectional side views of a proximal portion of a vibrational transmission member coupled with a transition connector for connecting to a vibrational energy source, according to an alternative embodiment of the present invention; and

FIG. 8C is a perspective view of the vibrational transmission member and transition connector of FIGS. 8A and 8B.

DETAILED DESCRIPTION OF THE INVENTION

Vibrational catheter devices and methods of the present invention provide for disruption of occlusions in blood vessels. The vibrational catheter devices generally include a catheter body, a vibrational energy transmission member disposed within the catheter body, and a distal head coupled with the vibrational transmission member and disposed at or near the distal end of the catheter body. The vibrational transmission member transmits vibrational energy, such as ultrasound energy, from a proximal vibrational energy source, such as an ultrasound transducer, to the distal head, causing the head to vibrate and, thus, disrupt vascular occlusions. A number of features of such vibrational catheter devices are described more fully below.

Referring now to FIG. 1, one embodiment of a vibrational catheter system 20 suitably includes a vibrational catheter device 10 and a vibrational energy generator 16. Catheter device 10 suitably includes a distal head 26 for disrupting occlusions, a catheter body 27, and a proximal end knob 12 for coupling catheter device 10 with a vibrational energy transducer 14. Vibrational energy transducer 14 is coupled with ultrasound generator 16 via a connector 28, and generator is coupled with a foot-actuated on/off switch 18 via another connector 29. Generator 16 provides vibrational energy to transducer 14 and, thus, to vibrational catheter 10. Catheter device 10 further includes a vibrational transmission member (or “wire”—not shown) that extends through the catheter body 27 and transmits energy from the transducer 14 to the distal head 26. Some embodiments of device 10 include a rapid exchange guidewire 13 and guidewire port, while other embodiments include a proximal guidewire port for over the wire guidewire delivery. In some embodiments, transducer 14 further includes a securing device 15 for enhancing coupling of catheter 10 to transducer 14. The various components of system 20 may be coupled via any suitable means. Connectors 28, 29 may comprise an electric cord or cable or any other suitable connecting devices for coupling on/off switch 18, generator 16 and transducer 14. In an alternative embodiment, on/off switch 18 is located on generator 16.

In addition to proximal knob 12, vibrational catheter device 10 may include one or more other various components, such as a Y-connector 11 including a fluid inlet port 17 (or aperture) for passage of irrigation fluid. Inlet port 17 may be removably coupled with an irrigation tube 24, which in one embodiment may be coupled with a fluid refrigeration (or “fluid cooling”) device 30. Refrigeration device 30 may, in turn, be coupled with a fluid container 32 via a connector tube 34. This irrigation apparatus may be used for introducing one or more fluids into catheter device 10. Fluid may be used to cool any part of the device, such as the vibrational transmission member, thus helping reduce wear and tear of device 10. In some embodiments, fluid inlet port 17 is located farther proximally on proximal knob 12, to allow fluid to be applied within knob 12. In some embodiments, refrigerated fluid is used, while in other embodiments irrigation fluid may be kept at room temperature. In various embodiments, oxygen supersaturated fluid, lubricious fluid, or any other suitable fluid or combination of fluids may be used, and again, such fluids may be refrigerated or kept room temperature. In an alternative embodiment to that shown in FIG. 1, refrigeration device 30 and fluid container 32 are combined in one device.

Generally, catheter device 10 may include any suitable number of side-arms or ports for passage of a guidewire, application of suction, infusing and/or withdrawing irrigation fluid, dye and/or the like, or any other suitable ports or connections. Also, vibrational catheters 10 of the present invention may be used with any suitable proximal devices, such as any suitable transducer 14, generator 16, coupling device(s) and/or the like. Therefore, the exemplary embodiment shown in FIG. 1 and any following descriptions of proximal apparatus or systems for use with vibrational catheters 10 should not be interpreted to limit the scope of the present invention as defined in the appended claims.

Referring now to FIG. 2, an enlarged view of catheter device 10 is shown. Proximal knob 12, Y-connector 11, inlet port 17, catheter body 27, distal head 26 and guidewire 13 are all shown. Catheter body 27 is generally a flexible, tubular, elongate member, having any suitable diameter and length for reaching a vascular occlusion for treatment. In one embodiment, for example, catheter body 27 preferably has an outer diameter of between about 0.5 mm and about 5.0 mm. In other embodiments, as in catheters intended for use in relatively small vessels, catheter body 27 may have an outer diameter of between about 0.25 mm and about 2.5 mm. Catheter body 27 may also have any suitable length. As discussed briefly above, for example, some vibrational catheters 10 have a length in the range of about 150 cm. However, any other suitable length may be used without departing from the scope of the present invention. Examples of catheter bodies similar to those which may be used in the present invention are described in U.S. Pat. Nos. 5,267,954 and 5,989,208, which were previously incorporated herein by reference.

Features of the present invention may be applied to any of a number of vibrational catheter devices. For more detailed description of exemplary vibrational catheter devices, reference may be made to U.S. patent application Ser. Nos. 10/229,371, 10/345,078, 10/375,903, 10/410,617, 10/722,209 and 0/927,966, which were all previously incorporated by reference. In various alternative embodiments, aspects of the present invention may be applied to any other suitable catheter devices.

Referring now to FIG. 3, a proximal portion of one embodiment of a vibrational catheter device 110 is shown in cross-section. An ultrasound transmission wire 140 extends from a transition connector 152 distally to a distal end (not shown) of catheter device 110. A catheter body 127 of device 110 is shown only in part, whereas catheter body 127 typically extends distally to (or near) the distal end of device 110. Catheter device 110 also includes a proximal knob 112 (or “housing”), having an inner bore 144 in which transition connector 152, a portion of vibrational transmission member 140 and one or more vibration absorption members 150 reside. Knob 112 is coupled with a Y-connector 111, which includes a fluid inlet port 117 (or aperture), and Y-connector 111 is coupled with catheter body 127.

In various embodiments, knob 112 may suitably include one or more surface features 142 for increasing the overall surface area of the outer surface of knob 112. Increased surface area enhances the ability of knob 112 to dissipate heat generated by vibrational transmission member 140 out of catheter device 110. Surface features 142 may have any suitable size or shape, such as ridges, jags, undulations, grooves or the like, and any suitable number of surface features 142 may be used. Additionally, knob 112 may be made of one or more heat dissipating materials, such as aluminum, stainless steel, any other conductive metal(s), or any suitable non-metallic conductive material(s).

In most embodiments, vibrational transmission member 140, wire, or wave guide extends longitudinally through a lumen of catheter body 127 to transmit vibrational energy from a transducer (not shown), connected to the proximal end of proximal knob 112, to the distal end of catheter device 110. Vibrational transmission member 140 may be formed of any material capable of effectively transmitting vibrational energy from the transducer, such as an ultrasound transducer, to the distal end of catheter body 127, including but not limited to metals such as pure titanium or aluminum, or titanium or aluminum alloys. Again, additional details of vibrational transmission members 140 may be found in the patent applications incorporated by reference above. Similarly, reference may be made to the incorporated patent applications for descriptions of knob 112, transition connector 152, vibration absorption members 150, Y-connector 111 and the like. For example, knob 112 and other features are described in detail in U.S. patent application Ser. No. 10/722,209, which was previously incorporated by reference.

Vibrational transmission member 140 typically passes from transition connector 152, through bore 144 and Y-connector 111, and then through catheter body 127. Fluid inlet port 117 is in fluid communication with a lumen in Y-connector, which is in fluid communication with a lumen extending through catheter body 127. Thus, fluid introduced into fluid inlet port 117 is typically free to flow into and through catheter body 127 to contact vibrational transmission member 140. Fluid may flow out of catheter body 127 through apertures in the distal head (not shown) or through any other suitable apertures or openings, such as apertures located in catheter body 127 itself. Any suitable fluid may be passed through fluid inlet port 117 and catheter body 127, such as refrigerated fluid, lubricious fluid, super-saturated saline or contrast/saline mixture, or the like. Cooling and/or lubricating vibrational transmission member 140 may reduce friction and/or wear and tear of vibrational transmission member 140, thus prolonging the useful life of vibrational catheter device 110 and enhancing its performance.

Additionally, the temperature and flow rate of a coolant liquid may be specifically controlled to maintain the temperature of vibrational transmission member 140 at a desired temperature within its optimal working range. In particular, in embodiments of the invention where vibrational transmission member 140 is formed of a metal alloy which exhibits optimal physical properties (e.g. super elasticity) within a specific range of temperatures, the temperature and flow rate of coolant liquid infused through fluid inlet port 117 may be specifically controlled to maintain the temperature of vibrational transmission member 140 within a range of temperatures at which it demonstrates its most desirable physical properties. For example, in embodiments of the invention where vibrational transmission member 140 is formed of a shape memory alloy which exhibits super-elasticity when in its martensite state, but which loses super-elasticity as it transitions to an austenite state, it will be desirable to adjust the temperature and flow rate of the coolant liquid infused through fluid inlet port 117 to maintain the shape memory alloy of vibrational transmission member 140 within a temperature range at which the alloy will remain in its martensite state and will not transition to an austenite state. The temperature at which such shape memory alloys transition from a martensite state to an austenite state is known as the “martensite transition temperature” of the material. Thus, in these embodiments, the fluid infused through port 117 will be at such temperature, and will be infused at such rate, as to maintain the shape memory alloy of vibrational transmission member 140 below its martensite transition temperature.

As mentioned above, in one embodiment, a super-saturated fluid may be used. Use of such fluids may enhance cavitation of an occlusion, help prevent unwanted tissue damage and/or the like. Such fluids are described, for example, in U.S. Pat. Nos. 6,676,900, 6,622,542, 6,613,280, 6,607,698, 6,605,217, 6,602,468, 6,602,467, 6,596,235, 6,582,387, 6,576,807, 6,558,502, 6,555,059, 6,533,766, 6,454,997, 6,387,324, 6,346,192, 6,315,754, 6,248,087, 6,235,007, 6,180,059, 6,142,971, 6,123,698, 6,030,357, 5,976,119, 5,957,889, 5,893,838 and 5,797,876, which are hereby incorporated by reference. In another embodiment, a mixture of contrast dye and saline may be used to achieve the same or similar results.

With reference now to FIGS. 4A-4C, one embodiment of a proximal portion of a vibrational transmission member 140 and a transition connector 252 for connecting to a vibrational transducer is shown. Transition connector 252 includes a proximal connection member 210 for attaching to a vibrational transducer, such as an ultrasound transducer. Connector 252 also includes a tapered distal portion 212 with a bore 216 extending into it from the distal end of connector 252. The proximal end of vibrational transmission member 140 extends into bore 216, and distal portion 212 is crimped down onto the proximal end of transmission member 140, using a crimping device 214 (crimping motion designated by hollow-tipped arrows in FIG. 4A). As shown in FIG. 4A, crimping force is applied to tapered distal portion 212 via crimping device 214 oriented parallel with a longitudinal axis along the length of ultrasound transmission member 140. Thus, crimping device 214 contacts and begins applying force to a proximal end of distal portion 212 before contacting and applying force to a distal end of distal portion 212.

By crimping distal portion 212 using the technique just described, and referring now to FIG. 4B, greater crimping force (solid-tipped arrows) is applied by distal portion 212 against an attached proximal-most portion of transmission member 140 than is applied against an immediately adjacent more-distal portion of transmission member 140 (hollow-tipped arrows). By applying this variable crimping force to transmission member 140, distal portion 212 of transition connector 252 absorbs vibrational motion occurring near its distal end, thus reducing stress on the transmission member 140 at the point where it enters bore 216. This stress reduction helps reduce wear and tear on transmission member 140, thus extending the useful life of the catheter device.

FIG. 4C shows an attached vibrational transmission member 140 and transition connector 252. In various embodiments, transition connector 252 may be a one-piece member or may alternatively include two or more pieces attached together. Proximal connection member 210 may include any suitable attachment means for removably attaching transition connector 252 to a transducer, such as but not limited to threads for screwing into complementary threads on the transducer or a snap-fit connector.

With reference now to FIGS. 5A-5C, an alternative embodiment of a transition connector 352 includes a proximal connection member 210 and a distal portion 312 having a bore 216, a proximal step 322 and a distal step 320. Proximal step 322 has a greater outer diameter than distal step 320. Thus, when crimping force is applied to distal portion 312, as shown in FIG. 5A (hollow-tipped arrows), crimping device 214 contacts only proximal step 322. Force is indirectly applied to distal step 320 through proximal step 322, but as depicted in FIG. 5B, greater force (solid-tipped arrows) is applied to transmission member 140 via proximal step 322 than via distal step 320. This variable crimping force allows distal step 320 to absorb vibrations of transmission member 140, thus reducing wear and tear.

FIG. 5C is a perspective view of the assembled transition connector 352 and vibrational transmission member 140.

Referring now to FIGS. 6A-6C, an alternative embodiment of a transition connector 452 includes a proximal connection member 210 and a distal portion 412 having a bore 416 with a widened distal opening 418. Referring to FIG. 6A, to attach transition connector 452 to vibrational transmission member 140, crimping force (hollow-tipped arrows) is applied via crimping device 214 oriented approximately along a longitudinal axis of the catheter. As shown in FIG. 6B, in this embodiment, crimping force closes widened distal opening 418 around transmission member 140. The crimping process thus applies less force (hollow-tipped arrows) against transmission member 140 via the distal-most part of distal portion 412 than via an immediately adjacent, more proximal part of distal portion (solid-tipped arrows). Again, this variable crimping force allows for vibrational absorption at the distal end of transition connector 452, thus reducing stress on vibrational transmission member.

FIG. 6C is a perspective view of the assembled transition connector 452 and vibrational transmission member 140.

Referring now to FIGS. 7A-7C, an alternative embodiment of a transition connector 462 includes a proximal connection member 210 and a distal portion 472 having a bore 478 that widens from its proximal terminus 476 to a widened distal opening 474. The widened distal opening 474 forms a space between opening 474 and transmission member 140. Referring to FIG. 7A, to attach transition connector 462 to vibrational transmission member 140, crimping force (hollow-tipped arrows) is applied via crimping device 214 oriented approximately along a longitudinal axis of the catheter. As shown in FIG. 7B, crimping force closes widened distal opening 474 around transmission member 140. The crimping process thus applies less force (hollow-tipped arrows) against transmission member 140 via the distal-most part of distal portion 472 than via an immediately adjacent, more proximal part of distal portion (solid-tipped arrows). Again, this variable crimping force allows for vibrational absorption at the distal end of transition connector 462, thus reducing stress on vibrational transmission member.

With reference now to FIGS. 8A-8C, an alternative embodiment of a transition connector 542 includes a proximal connection member 210 and a distal portion 512 having a bore 216. Referring to FIG. 8A, to attach transition connector 542 to vibrational transmission member 140, crimping force is applied via a distal crimping member 532 a (hollow-tipped arrows) and a proximal crimping member 532 b. Crimping members 532 may be part of one crimping device but controlled separately, or alternatively they may be two separate devices. In an alternative embodiment, one crimping member 532 may be used but applied sequentially to proximal and distal parts of distal portion 512. In any case, the force applied to distal portion 512 via proximal crimping member 532 b (solid-tipped arrows) is greater than the force applied to distal portion 512 via distal crimping member 532 a (hollow-tipped arrows).

As shown in FIG. 8B, the variably applied force (solid-tipped and hollow-tipped arrows) causes distal portion 512 to be more compressed near its proximal end, thus forming a proximal step 516 with a smaller outer diameter and a distal step 514 with a greater outer diameter. In turn, more crimping force is applied against transmission member 140 by proximal step 516 than by distal step 514, thus allowing for vibrational absorption by distal step 514.

FIG. 8C is a perspective view of the assembled transition connector 542 and vibrational transmission member 140, showing proximal step 516 and distal step 514 of distal portion 512.

Although the invention has been described above with specific reference to various embodiments and examples, it should be understood that various additions, modifications, deletions and alterations may be made to such embodiments without departing from the spirit or scope of the invention. Accordingly, it is intended that all reasonably foreseeable additions, deletions, alterations and modifications be included within the scope of the invention as defined in the following claims. 

1. A vibrational catheter for disrupting obstructions in lumens such as blood vessels, the catheter comprising: an elongate flexible catheter body having a proximal end, a distal end and at least one lumen extending longitudinally therethrough; a vibrational transmission member extending longitudinally through the lumen of the catheter body and having a proximal end and a distal end; and a transition connector attached to the proximal end of the vibrational transmission member for coupling the transmission member with a vibrational energy source, the transition connector comprising a bore into which the proximal end of the vibrational transmission member extends, wherein the proximal end of the vibrational transmission member is attached within the bore of the transition connector with variable attachment forces such that the transition connector exerts a substantially lower amount of attachment force on an attached distal-most portion of the vibrational transmission member housed within the bore so as to reduce stress on the vibrational transmission member at a distal end of the transition connector at least when the vibrational transmission member receives vibrational energy from the vibrational energy source.
 2. A vibrational catheter as in claim 1, wherein the vibrational energy source comprises a transducer.
 3. A vibrational catheter as in claim 2, wherein the transducer comprises an ultrasound transducer.
 4. A vibrational catheter as in claim 1, wherein the transition connector comprises multiple pieces attached together.
 5. A vibrational catheter as in claim 1, wherein the transition connector comprises a one-piece configuration.
 6. A vibrational catheter as in claim 1, wherein the transition connector comprises threads, which are complementary to threads on the vibrational energy source.
 7. A vibrational catheter as in claim 1, wherein the transition connector comprises a distal portion tapered proximally to distally, the distal portion extending from a proximal terminus of the bore to a distal opening of the bore.
 8. A vibrational catheter as in claim 7, wherein the vibrational transmission member is attached within the bore by crimping the tapered distal portion of the transition connector so as to apply greater crimping force to a wider, proximal part of the distal portion than to a narrower, distal part of the distal portion.
 9. A vibrational catheter as in claim 1, wherein the transition connector comprises a distal portion comprising: a first stepped portion having a first radius and extending distally from a proximal terminus of the bore; and a second stepped portion having a second radius smaller than the first radius and extending from a distal end of the first stepped portion to a distal opening of the bore.
 10. A vibrational catheter as in claim 9, wherein the vibrational transmission member is attached within the bore by crimping the first stepped portion, thus applying greater crimping force to the first stepped portion than the second stepped portion.
 11. A vibrational catheter as in claim 1, wherein the bore comprises: a first stepped portion having a first radius and extending distally from a proximal terminus of the bore; and a second stepped portion having a second radius greater than the first radius an extending from a distal end of the first stepped portion to a distal opening of the bore.
 12. A vibrational catheter as in claim 11, wherein the vibrational transmission member is attached within the bore by crimping the transition connector, thus applying greater crimping force to the first stepped portion than the second stepped portion.
 13. A vibrational catheter as in claim 11, wherein a space exists between the transmission member and the second stepped portion of the bore before crimping, and the space closes during crimping.
 14. A vibrational catheter as in claim 1, wherein the bore is tapered from a larger inner diameter at a distal opening of the bore to a smaller inner diameter at a proximal terminus of the bore.
 15. A vibrational catheter as in claim 14, wherein the vibrational transmission member is attached within the bore by crimping the transition connector, thus applying greater crimping force at the proximal terminus of the bore than at the distal opening.
 16. A vibrational catheter as in claim 14, wherein a space exists between the transmission member and inner diameter of the distal opening of the bore before crimping, and the space closes during crimping.
 17. A vibrational catheter for disrupting obstructions in lumens such as blood vessels, the catheter comprising: an elongate flexible catheter body having a proximal end, a distal end and at least one lumen extending longitudinally therethrough; a vibrational transmission member extending longitudinally through the lumen of the catheter body and having a proximal end and a distal end; and a transition connector comprising: a proximal connection member for attaching the transition connector to the vibrational energy source; and a bore having an opening in a distal end of, and extending into, the transition connector, for accepting the proximal end of the vibrational transmission member, wherein the proximal end of the vibrational transmission member is attached within the distal bore of the transition connector such that the transition connector exerts a substantially greater amount of attachment force on an attached proximal-most portion of the transmission member than on an adjacent portion of the transmission member immediately distal to the proximal-most portion so as to reduce stress on the vibrational transmission member at the distal end of the transition connector at least when the vibrational transmission member receives vibrational energy from the vibrational energy source.
 18. A vibrational catheter as in claim 17, wherein the vibrational energy source comprises a transducer.
 19. A vibrational catheter as in claim 18, wherein the transducer comprises an ultrasound transducer.
 20. A vibrational catheter as in claim 17, wherein the transition connector comprises multiple pieces attached together.
 21. A vibrational catheter as in claim 17, wherein the transition connector comprises a one-piece configuration.
 22. A vibrational catheter as in claim 17, wherein the proximal connection member of the transition connector comprises threads, which are complementary to threads on the vibrational energy source.
 23. A vibrational catheter as in claim 17, wherein the transition connector comprises a distal portion tapered proximally to distally, the distal portion extending from a proximal terminus of the bore to the opening of the bore.
 24. A vibrational catheter as in claim 23, wherein the vibrational transmission member is attached within the bore by crimping the tapered distal portion of the transition connector so as to apply greater crimping force to a wider, proximal portion of the distal portion than to a narrower, distal portion of the distal portion.
 25. A vibrational catheter as in claim 17, wherein the transition connector comprises a distal portion comprising: a first stepped portion having a first radius and extending distally from a proximal terminus of the bore; and a second stepped portion having a second radius smaller than the first radius and extending from a distal end of the first stepped portion to the distal opening of the bore.
 26. A vibrational catheter as in claim 25, wherein the vibrational transmission member is attached within the bore by crimping the first stepped portion, thus applying greater crimping force to the first stepped portion than the second stepped portion.
 27. A vibrational catheter as in claim 17, wherein the bore comprises: a first stepped portion having a first radius and extending distally from a proximal terminus of the bore; and a second stepped portion having a second radius greater than the first radius and extending from a distal end of the first stepped portion to the distal opening of the bore.
 28. A vibrational catheter as in claim 27, wherein the vibrational transmission member is attached within the bore by crimping the transition connector, thus applying greater crimping force to the first stepped portion than the second stepped portion.
 29. A vibrational catheter as in claim 27, wherein a space exists between the transmission member and the second stepped portion of the bore before crimping, and the space closes during crimping.
 30. A vibrational catheter as in claim 17, wherein the bore is tapered from a larger inner diameter at a distal opening of the bore to a smaller inner diameter at a proximal terminus of the bore.
 31. A vibrational catheter as in claim 30, wherein the vibrational transmission member is attached within the bore by crimping the transition connector, thus applying greater crimping force at the proximal terminus of the bore than at the distal opening.
 32. A vibrational catheter as in claim 30, wherein a space exists between the transmission member and inner diameter of the distal opening of the bore before crimping, and the space closes during crimping.
 33. A catheter comprising: a body having at least one lumen extending longitudinally therethrough; a transmission member extending longitudinally through at least a portion of the lumen of the body and having a proximal end; and a connector having a longitudinal bore for securing to the proximal end of the transmission member with attachment forces that vary substantially in magnitude along at least a portion of the longitudinal bore so as to reduce an operational stress on the transmission member at a distal end of the connector.
 34. A vibrational catheter as in claim 1, wherein the vibrational transmission member and the transition connector have an interference fit.
 35. A vibrational catheter as in claim 34, wherein the interference fit varies along the proximal end of the vibrational transmission member.
 36. A vibrational catheter as in claim 1, wherein the transition connector is crimped to the vibrational transmission member in at least a first position and a second position, wherein a first crimping force applied to the transition connector in the first position is greater than a second crimping force applied to the transition connector in the second position.
 37. A vibrational catheter as in claim 36, wherein the second position is distal to the first position.
 38. A vibrational catheter for disrupting obstructions in lumens such as blood vessels, the catheter comprising: an elongate flexible catheter body having a proximal end, a distal end and at least one lumen extending longitudinally therethrough; a vibrational transmission member extending longitudinally through the lumen of the catheter body and having a proximal end and a distal end; and a transition connector attached to the proximal end of the vibrational transmission member for coupling the transmission member with a vibrational energy source, the transition connector comprising a bore into which the proximal end of the vibrational transmission member extends, the bore tapering proximally to distally from a proximal terminus of the bore to a distal opening of the bore; wherein the proximal end of the vibrational transmission member is attached within the bore of the transition connector with variable attachment forces such that the transition connector exerts a lowest amount of attachment force on an attached distal-most portion of the vibrational transmission member housed within the bore. 